In recent years, personal authentication technologies using passwords and items (such as IC cards) have become generally widespread as a main pillar of information security. With these authentication technologies, however, the user may fail to authenticate themselves if they forget the password or lose the item. The technologies are also subject to leakage or theft, which may lead to authentication of other people. In contrast, authentication using biometric information is considered to be less likely to suffer from such risk. Biometric information eliminates the need for key inputs or carrying the item. Accordingly, biometric information provides an easy-to-use means of authentication, and is believed to be able to prevent authentication of a third party other than the right person. Examples of biometric authentication include fingerprints and the iris of the eye. Vein authentication, which reads the shape of blood vessels in the palm or finger, is being utilized at the bank ATMs, for example. Other authentication techniques using voiceprint, facial shape, handwriting and the like have also been put to practical use. However, even biometric authentication is subject to the potential of being breached by copying.
Meanwhile, various researches on the relationship between the human thought and behavior and the brain activity have been conducted over the years. Brain-Machine Interface (BMI) technology for controlling an external device or transmitting an intension to the others by focusing on biometric signals of brain activities, for example, is gaining attention.
The present inventors have proposed a virtual decision function and indicated a computation method therefor (see Non Patent Literature 1). Non Patent Literature 1 discloses an either-or behavior prediction method based on neural activity, taking a single neuron activity as an example.
The present inventors have also proposed an intension transmission assistance device and method for transmitting intensions by analyzing brain activity (see Patent Literatures 1 and 2). The techniques disclosed in Patent Literatures 1 and 2 make it possible to, for example, assist transmission of intensions of a motion-impaired person having difficulty speaking or writing, or a motion-impaired person having difficulty making input operations on various devices using hands or legs.
The present inventors have also proposed a technique for providing a map-like representation of in-brain information expressions using brain wave analysis for general subjects including able-bodied persons (see Patent Literature 3). The present inventors have also proposed a device and method for ordering, by brain wave analysis, objects to be investigated (see Patent Literature 4).
A prior art search has identified proposed authentication methods which utilize brain waves (see Patent Literatures 5 and 6). Patent Literature 5 proposes personal authentication based on the distance between a base based on an object person's brain waves and a base based on an object person candidate's brain waves, the bases being frequency components acquired from brain waves by Fourier transform, or time-domain components acquired from brain waves by correlation dimension analysis. Patent Literature 6 proposes a personal authentication method which, in addition to the verification of identity by existing biometrics authentication, detects when the valid user is forced to carry out an unauthorized operation. The method utilizes, for determining psychological states, information about brain waves, heart rates, amount of perspiration and the like as biometric information indicative of emotional features.